Small Engines (Lawn Mowers, etc.): 12HP briggs and stratton, briggs and stratton, hp briggs

Question
I have a 12 HP briggs and I am trying to adjust the carb. There is an adjustment on top of the carb and one at the bottom of the bowl. Is the one on top an idle adjustment or high speed. The model is  

Answer
hi paul  


what are the Model & Type and Date code numbers off engine  

but  i suspect the screw on the very top of carby  is idle mixture screw  and one on bowl is main jet hi speed  adjustment screw ?

let me know model and type numbers

cheers paul

i will send data